Dogwood tree named ‘Karen&#39;s Appalachian Blush’

ABSTRACT

A new and distinct cultivar of Dogwood tree,  Cornus florida , named ‘Karen&#39;s Appalachian Blush’, is provided. This cultivar is characterized by resistance to powdery mildew which is superior to any other white flowering dogwood.

CROSS-REFERENCE TO A RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/210,603, filed Jun. 9, 2000.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar offlowering dogwood which is resistant to powdery mildew. This dogwood isbotanically known as Cornus florida and hereinafter is referred to bythe cultivar name ‘Karen's Appalachian Blush’.

This new dogwood cultivar was discovered in a field planting ofapproximately 1,100,00 Cornus florida seeds in Decherd, Tenn. in 1995.‘Karen's Appalachian Blush’ is a white flowering dogwood which, to theknowledge of the inventors, is superior to any other white floweringdogwood with respect to powdery mildew resistance. Asexual reproductionof ‘Karen's Appalachian Blush’ by terminal cuttings harvested at theTennessee Agricultural Experiment Station in Knoxville, Tenn. has shownthat the unique features of this new dogwood cultivar are stable andreproduced true to type in successive generations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Photograph of a typical flower specimen of ‘Karen's AppalachianBlush’. This photograph is a closeup view of a typical flower of thiscultivar.

FIG. 2. A similarity index for various dogwoods.

FIG. 3. Cluster analysis of various dogwoods.

FIG. 4. Principal coordinate analysis of the relationships between thedogwoods.

Flower colors in the photograph may differ from the actual colors due tolight reflectance.

DETAILED DESCRIPTION OF THE NEW VARIETY

The parental lineage of this cultivar is unknown. ‘Karen's AppalachianBlush’ is a white flowering dogwood cultivar isolated from a fieldplanting of approximately 1,100,000 Cornus florida seeds in Decherd,Tenn. Seeds were bulked from collections of wild and landscape treesfrom Tennesee, North Carolina, Alabama, and Georgia. This cultivar maybe reproduced asexually by rooting cuttings and by grafting.

‘Karen's Appalachian Blush’ has white bracts which develop a pink blushalong the margins. The bracts are long and floppy, do not overlap, andare delicate in appearance. Upper pairs of bracts average about 13.3 cmlong by about 8.8 cm wide in size (n=30). Clefts at the ends of thebracts are pointed or flat and have little pigmentation. Flower petalsare yellow and flowers average 20 per inflorescence (n=15).

‘Karen's Appalachian Blush’ is, to the knowledge of the inventors,superior in resistance to powdery mildew to any other white floweringdogwood cultivar. This cultivar has been tested for three (3) years.Test plants were exposed to powdery mildew and assessed for resistanceto powdery mildew. Mildew scores for ‘Karen's Appalachian Blush’,control plants, and ‘Cherokee Brave’ were obtained using the followingscale: 0=healthy; 1=≦2% of foliage with signs or symptoms of powderymildew, 2=≦10% of foliage with signs or symptoms of powdery mildew;3=≦25% of foliage with signs or symptoms of powdery mildew; 4=≦50% offoliage with signs or symptoms of powdery mildew; 5=≦75% of foliage withsigns or symptoms of powdery mildew; 6=≦100% of foliage with signs orsymptoms of powdery mildew. Table 1 presents the data obtained over thelast three (3) years.

‘Karen's Year Appalachian Blush’ Control Score¹ ‘Cherokee Brave’² 19960.0 5.8(a) — 1997 0.0 6.0(b) 2.3 1998 1.0 4.8(c) 2.1 ¹Control plantswere (a) Cornus florida seedlings, (b) ‘Cherokee Sunset’, or (c)‘Cherokee Daybreak’ that were of similar age and size. ²‘Cherokee Brave’is a pink flowering dogwood cultivar which is the only cultivar known tothe inventors to possess resistance to powdery mildew.

DNA amplification fingerprinting was used to type ‘Jean's AppalachianSnow’, ‘Kay's Appalachian Mist’, and ‘Karen's Appalachian Blush’. Themethodology followed that of Trigiano and Caetano-Anollés(HortTechnology, 8:413-423 [1998]). Data, obtained from 235 locigenerated from genomic DNA using seven (7) arbitrary octomeric primers,was used to compare the powdery mildew resistant dogwoods of the subjectapplication to other dogwoods (including powdery mildew resistant linesand cultivars commonly found in nurseries). The sequences of the primerswere as follows: 1) GAGGCCTGT, 2) GTTACGCC, 3) CCTGTGAG, 4) GTAACGCC, 5)GACGTAGG, 6) GATCGCAG, And 7) GTATCGCC. DNA amplification fingerprintinganalysis as well as the cluster and principal coordinate analysis werecompleted using the NTSYS PROGRAM, pc version, 2.2 (Exeter Software, 100N. Country Road, Sedtauket, N.Y. 11733). A similarity index is providedin FIG. 2. FIG. 3 depicts the resulting cluster analysis. FIG. 4 depictsthe principal coordinate analysis of the relationships between thedogwoods.

The abbreviations found in the Figures are as follows: AS=‘AppalachianSpring’, KAM=‘Kay's Appalachian Mist’, JAS=‘Jean's Appalachian Snow’,C9=‘Cloud Nine’, KAB=‘Karen's Appalachian Blush’, CP=‘CherokeePrincess’, SPR=‘Springtime’ and CB=‘Cherokee Brave’. All are white bractdogwoods except, CB, which is red.

DETAILED BOTANICAL DESCRIPTION

The following observations, measurements, and comparisons describe thiscultivar grown in Knoxville, Tenn. under container nursery conditionswhich approximate commercial production conditions. Dogwoods used forthis description were about five (5) years old and were grown intwenty-five (25) gallon containers. Plant hardiness is expected to bezones 5-9.

The following description uses color references to The RoyalHorticultural Society Colour Chart, except where general terms ofordinary dictionary significance are used. All color ratings were onadaxial surfaces. Color ratings for abaxial surfaces were not obtainedbecause reflected/refracted light, due to the density of pubescence onabaxial surfaces, made accurate color determinations difficult orimpossible. Measurements are provided as a range with the middle valueproviding the average (lower limit<average value<upper limit).

Botanical classification: Cornus florida, cultivar ‘Karen's AppalachianBlush’.

Parentage: Unknown.

Propagation:

Type.—Terminal softwood cuttings.

Time to initiate roots (in June).—About 3-4 weeks at about 25-30° C.

Rooting habit.—Profuse from base of cutting.

Rooting hormone.—5,000-10,000 ppm; five (5) second quick dip of DIP ‘N’GROW (1% IBA, 0.5% NAA) (Dip ‘N’ Grow, Inc., Clackamas, Oreg.).

Intermittent mist.—Six (6) seconds every six (6) minutes.

Light.—30-50% shade cloth over propagation bench.

Media.—Peat-perlite.

Plant description:

Plant form and growth habit.—Perennial deciduous tree, mostly uprightwith horizontal branching.

Plant size.—A five (5) year old tree will attain a height of about 240cm and a width of about 110 cm.

Vigor.—Similar to other Cornus florida cultivars.

Branching habit.—Moderate, branch crotch angles of about 20-40° to maintrunk.

Main stem/trunk description.—Diameter: About 3.3 cm; bark texture:smooth; bark color: gray 201C.

Lateral branch description.—Branch angle of about 45° with a range of40-48°.

Foliage description:

Arrangement.—Simple, opposite; leaves mostly crowded towards branchapices.

Leaf blade length (cm).—About 9.9<11.2<12.5 (n=5).

Leaf blade width (cm).—6.0<7.5<8.8 (n=5).

Petiole length (cm).—1.1<1.4<1.7 (n=5).

Petiole diameter (mm).—About 1.1<1.3<1.45 (n=5).

Shape.—Broadly ovate.

Apex.—Acuminate, leaf tips mostly flat.

Base.—Acute to cuneate, about 10% unequal.

Margin.—Entire, slightly undulate.

Texture.—Upper surface: Nearly glabrous. Lower surface: leaf hairsprofuse on veins and vein axils (μ) — 16<25<36.

Color.—Yellow green 146C.

Leaf vein arrangement.—Six (6) pairs, mostly opposite. Petiole reflexed80°-90° from plane of leaf blade.

Bipolar trichomes.—Upper surface — low density (μ) — 6<7.2<10 Lowersurface (μ) — 6<9.8<14.

Flower description:

Fragrance.—None observed.

Flower bud size.—Width: 6.4 mm (widest diameter). Length: 5 mm (base totip).

Shape of involucral bracts.—Obovate/pandurate.

Apex shape of involucral bracts.—Mucronate.

Base shape of involucral bracts.—Cuneate.

Number of bracts. 4 (in two pairs).

Natural flowering season.—1999: about 15 days (April 10 through April25). 2000: about 16 days (April 5 though April 21). 2001: about 15 days(April 12 through April 27).

Inflorescence arrangement.—Bracts long and floppy; do not overlap.

Inflorescence diameter.—About 27 cm wide.

Bract dimensions.—Upper bracts about 13.3 cm long by about 8.8 cm wide.Inflorescence is 5.9 mm wide; anther length is 1.2 mm. Floraldevelopment is asynchronous among inflorescence.

Color (abaxial and adaxial surfaces).—White (155D) bracts develop a pinkblush (73B) suffused along the margin. Clefts are pointed or flat withlittle red-purple (60A) pigmentation.

Sepals.—Typically 4.

Stamens.—Typically 4.

Pistil.—Typically 1.

Flower number.—20.

Petal color (abaxial and adaxial surfaces).—Yellow green 151B.

Ovary.—Bilocular with each locule having 1 ovule.

Fruit description:

Berry type.—Drupe (about 14 mm by 7 mm) aggregated in one mass.

Color.—10R(6/10) using Munsell Color Chart for Plant Tissues (MunsellColor, Baltimore, Md. 21218).

Disease resistance: This cultivar demonstrated outstandng resistance topowdery mildew superior to that of any other white flowering dogwoodcultivar known to the inventors. No susceptibility to other diseases orarthropod pests was observed.

What is claimed is:
 1. A new and distinct cultivar of Dogwood tree,Cornus florida, named ‘Karen's Appalachian Blush’, as illustrated anddescribed.